Custom Etched Foil Heaters- Med Device Solutions

Product Announcement from Thermal Circuits, Inc.

The Medical Electronics industry demands precise solutions to highly sensitive applications. Thermal Circuits, Inc. etched foil heaters provide the OEM with the inherent advantage to distribute wattage infinitely and exactly. Combining this feat, with Thermal Circuits' skill in material science and the industry's broadest selection of element and dielectric materials, often yields a competitive advantage for the OEM.

Thermal Circuits etched-foil heaters are used in blood analyzers, dialysis instrumentation, DNA analysis, genetic testing systems, invasive probes, life support fluid warmers, sterilizers, tissue processors, transportable incubators, thermal cyclers, and hybridization ovens.

Whether or not an application evolves into a final product, the OEM's scientists, engineers and managers can be assured that Thermal Circuits team of application engineers are the best choice to meet their individual design challenges. Through research, development and innovation, Thermal Circuits provides effective solutions incorporating conductive surface heaters, convective air/gas heaters, and infrared heater assemblies.

We can help!  Curing ill-performing thermal systems requires expert diagnosis and root cause determination by engineers trained in heat transfer and thermal analysis. Thermal Circuits' team of application, design, and quality assurance engineers are uniquely qualified to provide your company with solutions to ensure your successful thermal application.

While hybridization ovens present very specific heating challenges, heating assemblies play a critical role in a variety of medical instruments. Highly sensitive applications, such as blood analyzers, dialysis instrumentation, sterilizers and incubators demand precise solutions to heating requirements.

Utilizing etched-foil heaters in these devices provide the inherent advantage of distributing wattage infinitely and exactly, making the units more reliable. By eliminating wire failure, devices are safer, run cooler and last longer. Etched-foil heaters are available with a variety of dielectric encapsulations, to meet varying temperature requirements, as well as provide solutions for applications requiring low outgassing and resistance to radiation, chemicals and solvents.

Etched-foil elements are able to operate at very high densities due to the larger surface area covered by the foil track. The element is created by acid etching a circuit in resistance alloy foil. This process ensures excellent circuit pattern repeatability and allows the design of complex heat distribution patterns within the heater area. By not confining the wattage to tightly spiraled coils, the etched-foil element heating system runs cooler and lasts longer, still with the same power. Etched-foil elements also provide faster heat transfer resulting in longer heater life in high power applications.

With shorter conductors covering a larger surface area of the element, the design of the etched-foil element inherently reduces the stress on the element itself, making it less likely to break and increasing reliability. In addition, the etched-foil element adds an extra level of safety because the wire is covered with dielectric insulation,thereby,not allowing the foil element to short out under any condition.

Etched foil heaters

  • fit snug to the surface
  • mount away from the surface - radiate or are air driven
  • can adapt to unlimited shapes and offer electric insulation options
  • distribute heat evenly and can provide profiled heat in a wide range of temperatures from warming to cooking.

The etched foil elements are compatible with Thermal Circuits High Temperature Binder Inorganic and Organic Coatings and with fabrication materials such as fiberglass cloth, fiberglass mat, mica, and ceramic fiber insulating carriers. The coatings protect and immobilize the elements yet allow them to expand and contract, cycling at watt densities two to three times greater with temperatures up to 1200° F.

The versatility of etched foil heaters assists designers in creating products that are high-performance, efficient and cost-effective.

The Benefits of Using Kapton® Polymide Heaters

DuPont™ Kapton® is a polyimide film when combined with etched foil elements, produces very thin flexible heaters. Since Kapton® maintains its excellent physical, electrical, and mechanical properties over extreme temperatures; it is considered a unique industrial material. Kapton®/Polyimide is compatible with foil element alloys as inconel, nickel, copper, Balco and many stainless steels. These dielectric insulators have low outgassing properties, are resistant to a myriad of chemistries, and can be produced with sundry internal adhesive systems that permit higher watt densities and operating temperatures. Kapton® contains properties that make it ideal for many applications in a wide range of industries. It is reliable, rugged and has a very high dielectric constant.

Typical Applications

  • Personal Care and Kitchen Appliances
  • Automobiles, Trucks and SUVs
  • Avionics, Aerospace and Military
  • Electronics Industry
  • Food Services and Restaurants
  • Medical Devices and Science
  • Reprographics and Office Equipment
  • Semiconductors and Wafer Processing
  • Transportation

Many of these applications are based on the excellent balance of electrical, thermal, mechanical, physical, and chemical properties of Kapton® over a wide range of temperatures. It is this combination of useful properties at temperature extremes that makes Kapton® a unique industrial material.


  • Custom Kapton® Heaters UL & CSA Recognized
  • -269°C up to 400°C(Maximum)
  • Chemical Resistant
  • Formable and Flexible
  • Bondable to Metalwork
  • Dimensional stability
  • Tear/ Cut Resistance
  • High Dielectric Strength
  • Minimal out-gassing in high vacuum environments
  • Thinnest, most rugged flexible heater

How Kapton is Synthesized
Kapton® is synthesized by polymerizing an aromatic dianhydride and an aromatic diamine.

  • It has excellent chemical resistance since there are no known organic solvents for the film
  • Kapton® does not melt or burn as it has the highest UL-94 flammability rating: V-0. The outstanding properties of Kapton® permit it to be used at both high and low temperature extremes where other organic polymeric materials would not be functional
  • Adhesives are available for bonding Kapton® to itself and to metals, various paper types, and other films

Features of Polyimide Flexible Heaters

  • Various adhesive systems used with Teflon® and acrylic derivatives
  • UL component recognition available
  • Suitable for vacuum environments (NASA-RP-1061)
  • NASA approved materials for space applications (S-311-P-079)
  • Resistant to most chemicals: acids and bases
  • Radiation resistant to 10^6 rads (custom option)

Technical Specifications
Kapton® can withstand temperatures as low as -269°C and as high as 400°C, and still retain its properties.

Kapton® polyimide film is a registered trademark of DuPont™ and has more than 45 years of proven performance as the material of choice in applications involving temperature extremes and harsh environments.

About Thermal Circuits:

Thermal Circuits Inc. is a 64 year-old manufacturer of surface heaters, air heaters, molded heaters, heater assemblies, and infrared panel emitters. We service a wide variety of markets and geographic areas and, through continuous quality improvement, strive to maintain world-class leadership in all aspects of our business.

Strong growth prompted the construction in 1996 of a single-storied, 52,000 square foot building and remains Thermal Circuits' home. Still in Salem, the company is owned by its corporate partners and is the anchor company in a newly-developed industrial park. This facility is state-of-the-art and second to none.  Due to continuing growth, in 2017 and 2018 Thermal Circuits expanded its manufacturing and office spaces to 88,000 square feet.

Core Competencies:

A “solution” designer and manufacturer of custom, etched foil heaters and assemblies, would welcome the opportunity of creating an affordable heater designed to your application’s requirements.

Our core competencies for these conductive, convective and radiant heaters include:

  • Application Engineering that is responsive and experienced. You can be assured that we will provide an optimal, reliable solution. Let us help you turn your company’s opportunity into a competitive advantage.
  • Thermal Uniformity is attained by varying the heater’s watt density, thereby, compensating for heat losses.
  • Thermal Responsiveness is a function of the heater’s low mass. Heating and cooling are virtually instantaneous.
  • Repeatability through Thermal Circuits’ photo etch process that sustains part-to-part consistency.
  • Innovative Manufacturer
    • Recognized for using the broadest range of materials
    • Dielectrics compatible with integration and challenging environments.
    • Element/alloys developed for increased capabilities and lower costs.
  • Integrated Sensors
    • Thermistors, RTDs, semiconductor-type, thermocouples, thermostats and thermal fuses.
  • Turnkey Assemblies
    • Metalwork, heat sinks, wire harnesses and flex circuits.
  • Space and Weight Efficient
    • As thin as 0.004”.
  • Energy Efficiency
    • 70% of the surface area is covered with an active element. This enables the element to run cooler and with longer wavelengths of light, which transfers heat more effectively.
    • The etched foil element’s inherent low mass has less thermal inertia, which enables lower operating costs.

Industry Market Applications:

 Quality Insurance:

Quality is paramount at Thermal Circuits. We are a certified manufacturer of critical components and an approved ship-to-the production line, zero defect supplier. Our contractual customers perform no incoming inspection of our heaters and heater assemblies. Thermal Circuits' Quality Assurance Department is equipped, staffed, and administered to the requirements of MIL-1-45208A to which we are approved by major subcontractors.

The Quality Management System of Thermal Circuits has been audited and is compliant with the requirements of and is registered to ISO 13485:2003.

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